Free planning tool
Compound interest calculator
See what an initial amount and regular deposits could become. Adjust the assumptions, then compare what you put in with the interest projected over time.
Your assumptions
Your projection
Estimated ending balance
Starting amountDepositsInterest
Year-by-year growth
Values are shown in US dollars and rounded for display.
| Year | Ending balance | Total deposited | Interest |
|---|
Understand the estimate
How this calculator works
The annual rate you enter is treated as a fixed nominal rate. We turn it into an effective rate for each deposit interval using (1 + annual rate ÷ compounding periods)^(compounding periods ÷ deposit periods). Each deposit is added before or after that interval's growth, based on your selection. Interest stays in the balance and can earn more interest.
When deposit and compounding schedules differ, the model spreads effective growth evenly across deposit intervals. It does not model exact calendar dates, taxes, fees, inflation, or changing returns. Negative rates are allowed to explore losses; projected interest can be negative. This is an educational estimate, not a guaranteed outcome or investment advice.
Read the complete calculation method and a worked example. For more context, see the Investor.gov calculator and the CFPB explanation of compound interest.
Learn more about monthly contributions, compounding frequency, or review worked compound interest examples.